Self-timed reaction-mass compass

ABSTRACT

Two horizontal discs of identical mass and dimensions are rotated in opposite directions at identical and fixed speed. Each disc is pierced by a radial slot. Coincidence of said slots provides an index spot on a compass card. Said coincidence is independent of the device support and holds its direction in space despite support movement and rotation. The discs may be rotated by any means. A counter may be employed to read out the slot-coincidence position in degrees relative to any fixed angular position about the axis of said discs.

- [22 Filed:

United States Patent [191 Alth 1 SELF-TIMED REACTION-MASS COMPASS [76]Inventor: Max Alth, 6 Tamarack Rd., Port Chester, NY. 10573 [21] Appl.No.: 79,557

[52] U.S. CI. 33/300 [51] Int. Cl G01c 17/00 [58] Field of Search 33/204D; 310/114, 115

[5 6] References Cited UNITED STATES PATENTS 488,305 12/1892 Bradley310/115 X 2,370,000 2/1945 Best 33/222 R 2,611,191 9/1952 Noxon et al.33/204 Q X 3,561,129 2/1971 Johnston 33/226 R FOREIGN PATENTS ORAPPLICATIONS 288 7/1876 Great Britain 33/300 Feb. 26, 1974 12/1930Germany 33/204 D 9/1941 Great Britain 33/204 GB Primary Examiner--RobertB. Hull [57] ABSTRACT Two horizontal discs of identical mass anddimensions are rotated in opposite directions at identical and fixedspeed. Each disc is pierced by a radial slot. Coincidence of said. slotsprovides an index spot on a compass card. Said coincidence isindependent of the de- Vice support and holds its direction in spacedespite support movement and rotation. The discs may be rotated by any.means. A counter may be employed to read out the slot-coincidenceposition in degrees relative to any fixed angular position about theaxis of said discs.

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The invention herewith disclosed provides a compass which is independentof the earths magnetic poles, and which is considerably more accurateover a long period of time than'the gyroscopic compass.

The present invention provides an improved basis for an inertialguidance system.

The present invention provides a compass which can easily be read bymachine, i.e., electonic read-out and display at any desired distancefrom said device.

The present invention yields angular position in digital form.

FIGS. 1a and lb are simplied views of the essential elements of thepresent invention.

FIG. 2 shows a direct positional read-out arrangement.

FIG. 3 is a simplified plan view of the essential AC drive arrangementshown in FIG. 5, and utilized basically in'FlG. 4. I

FIGS. 4a and 4b show the present invention with associated electronicequipment for electronic read-out and display, plus direct visualposition read-out.

FIG. 5 shows the AC drive arrangement.

FIG. 6 shows how the discs may be air driven.

FIGS. 7a and 7b show how atomic energy may be used to drive the discs.

PRINCIPLE OF OPERATION Referring to FIGS. 11; and lb, 2 and 3 are discsrotating in opposite directions on shaft 6; 4 and 5 are radial slotsthat pass through said discs. 7 represents a line of sight, while 8indicates what will be seen at the termination of said line of sight. Inthe plan view, FIG/lb, 4 is a top view of the slot passing through disc2.

The earth may be considered a time-mass compass. A sailor refers to hischromometer to relate the position of the sun to his longitude and afixed point of time; namely Greenwich time.

To duplicate the earth as a compass, one would need to duplicate itsmass. However, by using two masses rotati'ng in opposite directions,high timemass accuracy can be obtained. So long as the two discs rotateat a fixed frequency or speed, slot 4 FIG. 1a) and slot 5 will crosseach other at equal intervals in time and therefore the slots will pointin the same direction at that-instant despite the turning of the compasscard shown beneath the discs.

. In FIG. 2, one means for rotating the two discs at a fixed speed bymeans physically separated from said discs is illustrated. Other meansare shown in figures following.

In FIG. 2, '10 and 11 are the discs, is the shaft on which they rotatefreely, 22 and 23 are supporting means. Power to the discs is impartedby a fixed solenoidal coil 19 powered by an oscillator. Each disc comprises one half of a synchronous motor. Coils 16 and 1 7 are solenoidalcoils within the field of the driving coil 19. 16 and 17 are eachconnected to a ring of solenoids, two of which are marked 14 and 15. 4andS indicate the slots passing through said discs, while indicates thelight beam. 24 is one support for shaft 20 and includes a fixed compasscard, while 21 provides the other bearing for the same shaft, 20.

No ferrous material is used with coils 19,16 or 17. This is done tominimize whatever lockingaction may be present between these coils. Coil19 energizes coils l6 and 17 which then energize the solenoids, whichare arranged with their axesevenly spaced about shaft 20 and parallelthereto. In FIG. 2, 12 is a small brake, used to retard one discmomentarily.

In operation the discs are brought to synchronous speed by externalmeans. Either the brake 12 or the power is momentarily disconnectedtoretard one or both discs until the slot is over North. From that momenton, as long as power continues, slot coincidence is independent of rotorsupport. A change in driving frequency does not alter this as both discsare equally affected.

FIG. 3 is a partial plan view illustrating an arrangement of solenoidsalternating with permanent magnets. Another view of this arrangementfrom the side, illustrating the relationship between the solenoids andmagnets in the upper and lower discs may be seen in FIG. 5.

In FIG. 3, 19 is the driving coil connected to a source of alternatingcurrent. 36 is the circumferential coil mounted on rotor 10, which isconnected to the solenoids indicated by 37. The permanent magnets are38. The slot is 4 and the shaft is 27.

FIG. 4 a shows how the AC drive shown in FIGS. 3 and 5 may be utilizedtorotate the two discs. Essentially there is the same basic arrangementof parts, some of which have been omitted for clarity. 27a is the shaft,13 is the slot, 30 is the case, 29 is a translucent section of glasswith compass points enscribed, 22a indicates a number of light bulbsconstantly on, 23a is another piece of translucent glass; 24a and 25aare photoelectric cells and 26 is a light shield. 19 is the externalcoil connected to alternating current.

Case 30 in FIG. 40 may be evacuated to improve operation and reducepower requirements. For more efficient light reflection, translucentplate 26 may be partially silvered so that more of the light comingthrough the slots in coincidence is reflected onto the photo cell 25a.

Referring to FIG. 4a, assume for discussion a crystal controlledoscillator with a fixed frequency of 3,600 Hz driving the counter at therate of one count per cycle. The counter starts when light strikes 24aand stops when light strikes 25a, displaying the last number when turnedoff.

Assume futher that we have rotors with 20 poles fewer poles are shown inFIG. 3 for simplicity).

Rotor speed in RPS 2I-Iz/poles I The alternating current supplied theamplifier is reduced by a factor of ten; thus the rotor would revolve at36 revolutions per second. As the counter is being driven at a rate of360 counts per second; there is just enough time for the counter to gofrom zero to 360 every time the rotor makes one complete revolution.Thus, with the rotors at speed, the counter is started when lightstrikes 24a and stopped when light coming up through the coincident xslots strikes 25a.

In operation the variable oscillator is initiated at zero cycles andslowly brought up to 360 Hz, thus bringing the rotors to speed. Thevariable oscillator is disconnected and the rotors are switched to thefixed fre-' quency oscillator. To bring the slots into coinciddnce over0, a brake not shown, but illustrated at 12 in FIG. 2 may be used.

Once coincidence is over 0, the counter will read out whateverrotational change occurs to the supporting means.

It should be noted that in this arrangement the rotors are virtuallyisolated from their supporting and driving means; changes in basefrequency affect both rotors and counter identically and thus are selfeliminating. Rotor speed is synchronized with frequency and the oppositerotor. Slot coincidence is not locked to base frequency, but will shiftwith difference in the moment of inertia between the two rotors; slotcoincidence will drift in the direction of the heavier rotor. Also, slotcoincidence will eventually fa-ll prey to cumulative frictionaldifferences, i.e., slot coincidence will travel angularly in thedirection of that disc with the greatest coefficient of friction.

Neither of these two considerations are insurmountable, as correctionscan be made empirically. Longterm mass and frictional changes, however,do in theory appear to be the limiting factors in long term stability.

FIG. 5 shows how permanent magnets are alternated with solenoids to cutrotational speed in half. 36 is the circumferential coil on the rotor;37 indicates solenoids and 38 indicates permanent magnets.

FIG. 6 illustrates how the rotors may be driven by compressed air. 40indicates the two air inlets and supports, 41 is the slip joint, 42 theshaft, which rotates, 43 indicates the rotors, 44 is an air inlet holein the rotor leading to the annulus and 45 is an exhaust hole.

FIG. 6 shows how the rotors may be driven by radioactive material. 50 isthe shaft, 51 is one rotor, while 52 is the reactive atomic engines leadshield. 53 is the radioactive material and 54 is a magnett. Certainradioactive material in the presence of a magnetic field selectivelydischarges electrons. Such a discharge could be used to power therotors.

I claim:

1. A compass comprising two like discs, each pierced therethroughaxially by a radial slot; a case within which said discs are positionedface to face; a compass card mounted on said case coaxially of saiddiscs; a common central axis shaft for said discs positioned verticallyin said case; each of said discs being freely rotatably mountedcoaxially on said shaft and comprising a coaxial coil circumferentiallythereon and a plurality of solenoids and permanent magnets in equalnumber mounted on said disc anddistributed evenly and alternately aboutthe disc axis with their magnetic axes parallel to said axis, and saidsolenoids being connected to said coil; source of alternating electriccurrent; and a third coil fixed relative to said case coaxially withsaid shaft and of inner circumference slightly larger than said discs;said third coil being connected to said source and positioned with itsalternating current field common to both said coils on said discs, sothat when said discs are brought to synchronous speed, each spinning ina direction opposite to the other, alternating current energy istransferred from said third coil to the two said circumferential coilson said discs and they spin at synchronous speed in opposite directions,

2. A compass as claimed in claim 1, further comprising a steady sourceof light in fixed position relative to the case beneath the lower ofsaid discs; a photolcell in fixed position between the discs; aplurality of photocells in fixed position above the upper one of saiddiscs; bands shielding said plurality of photo-cells from light otherthan that which may come up from below; and an electronic counterconnected to said alternating current source; and said photo-cellbetween the discs and said plurality of photo-cells .above the discsbeing suitably connected to said electronic counter so that said photocell between the discs initiates counting and said plurality of photocellsstops the counting.

2. A compass as claimed in claim 1, further comprising a steady sourceof light in fixed position relative to the case beneath the lower ofsaid discs; a photo1cell in fixed position between the discs; aplurality of photo-cells in fixed position above the upper one of saiddiscs; bands shielding said plurality of photo-cells from light otherthan that which may come up from below; and an electronic counterconnected to said alternating current source; and said photo-cellbetween the discs and said plurality of photo-cells above the discsbeing suitably connected to said electronic counter so that said photocell between the discs initiates counting and said plurality of photocells stops the counting.